We recently ran an anatomy workshop for Yoga Instructors with Meadowlark Yoga. I ran a session on the most common injury in Yogis; left knee medial meniscus tears. It had such fantastic feedback that I thought I would repeat it here to help spread the message further. Obviously it is here without the cadaveric specimens but I hope the drawings and your imagination can fill the gaps.
The most common injury in Yoga people in left knee medial meniscus tears. Why should that be? I’m hoping that if I explain a little of how the knee joint works you may be able to work out what the problem is and what can be done to mitigate it.
The knee is the most complex joint in the body. You only have to look at the diagrams to appreciate all the tendons and moving parts that make up the joint.
To keep it simple, the joint is not a hinge joint as it is often described. The articulating surface of the femur is a lot larger than the articulating surface of the tibia in the lower leg. As the joint hinges it also has to slide to ensure these surfaces stay in contact with each other. It is the role of the cruciate ligaments, both anterior and posterior, to ensure that the femur does not slide too far in either direction
To further increase the surface area at the top of the tibia we find two semi circular shaped cartilage wedges (thicker at the edge of the knee, so almost triangular in cross section). These increase the surface area and also help to hold the femur in place on top of the tibia.
These semi circular wedges are the menisci, one lateral – to the outside of the knee, and one medial – towards the inside of the knee joint. As you can see in the diagram above, the lateral meniscus is not connected to the ligaments at the side of the joint and so it is held in place only at the two end of the C shape. It can move around more easily inside the joint than the medical meniscus which is joined to the ligament at the inside of the knee joint.
As the knee flexes (foot moved towards your bottom) the menisci move to the back of the joint. If your knee is fully flexed then your menisci are quite safely held at the back of the joint. How many people do you know who can get their foot all the way to their bottom? If your leg isn’t fully flexed then the menisci are in the process of moving backwards.
The knee isn’t only a sliding hinge joint, it also has a degree of rotation. If you have a straight leg and rotate the limb then all of that motion is coming from the hip. If you now bend your leg you can get a few degrees of rotation at the knee joint.
If you medially rotate your lower leg, turn your big toe in towards the centre of your body then this will cause the medial meniscus to move forwards and the lateral one to move back. Just pause for a moment and imagine the two bones on top of each other, rotating and you can see what would happen to the menisci if they are just held at the end of their C shape.
Now imagine what you are asking your knee to do if you medially rotate your lower leg whilst also flexing your knee joint. This is the equivalent of reaching down, grabbing your foot and lifting it up towards your stomach, something you see quite a lot in an exercise setting. The flexing motion is asking your menisci to move back and the medial rotation is asking your medial meniscus to move forwards. You are trying to move the same piece of cartilage in two opposite directions at the same time!
So why left knee injuries?
It’s traditional to go into the lotus pose in yoga with your right knee first. This means to bring the left knee into this pose you have to lift it over the right leg that is already in position. It doesn’t matter how flexible you are – that is an impossibility. The result, you are twisting a not fully flexed knee. It is a potential risk for the meniscus.
What can you do to help it? Don’t do lotus or if you are not prepared to go that far – or you can’t do lotus anyway so you want to know how to protect your knees for other poses – try to laterally rotate your lower leg if it isn’t fully flexed.
Rather than reaching down and grabbing your toes, reach underneath and grab the heel. Ensure that if you move your lower leg at all that the toes would rotate outwards rather than inwards.
I’ve written about anatomical issues with the lotus position for yoga moo if you want to see the article on hip rotation than click here